Pneumatic starter motors are used for cranking internal combustion engines for starting purposes and are typically used for large engines and engines operating in environments where electric starting systems can be hazardous such as in mines.
Some known pneumatic starter motors have utilised a arrangement in which a flow of air generally parallel to the axis of rotation of a turbine wheel interacts with turbine elements to drive the wheel in rotation. In some other known pneumatic starter motors, air is directed radially with respect to the axis of rotation of a turbine wheel to interact with radially oriented elements which drive the wheel in rotation. Whilst both arrangements have been used to provide satisfactory air motors for pneumatic starters and other applications, improvements in output and operating characteristics are continuously sought.